1. Field of the Invention
The present invention relates to flexible seals, and more particularly to a flexible seal for sealing off a vacuum chamber at the side of a rotatable seed disk within the housing of a vacuum seed meter.
2. History of the Prior Art
It is known in the field of agricultural implements to provide a seed meter which meters or dispenses individual seeds from a seed mass during a planting operation. In seed meters of the air type as opposed to mechanical seed meters, blowing air or vacuum is used to hold individual seeds on a moving member such as a seed disk for eventual discharge. Examples of air seed meters using blowing air or pressure are provided by U.S. Pat. Nos. 3,888,387 of Deckler, 4,047,638 of Harrer and 4,074,830 of Adams. Examples of seed meters in which vacuum is used to hold individual seeds in place on the moving member are provided by U.S. Pat. Nos. 3,608,787 of Grataloup and 3,990,606 of Gugenhan. Such patents describe a variety of different arrangements using different configurations of a movable member for picking up, holding and then discharging the seeds. Such arrangements therefore provide a variety of different configurations and apparatus for communicating the blowing air or pressure or the vacuum, depending upon the type of air seed meter, to the moving member.
A different type of vacuum seed meter is described in a co-pending application of Lundie et al, Ser. No. 546,834, filed Oct. 31, 1983 (continuing application Ser. No. 883,851 filed July 10. 1986) with the present application. The vacuum seed meter described in the Lundie et al application disposes a rotatable seed disk within the hollow interior of a generally cylindrical housing which is mounted at the bottom of a seed hopper. Seeds from the hopper flow into a seed chamber within the housing on a side of the seed disk having a plurality of seed cells therein. As the seed disk rotates, the seed cells which are arranged in a circumferential array about the seed disk agitate, accelerate and then capture individual seeds therein. As the seed cells rise above the seed mass within the seed chamber, the individual seeds are held within the cells by vacuum from a source coupled to a vacuum chamber on the opposite side of the seed disk. The vacuum communicates with apertures at the bottoms of the seed cells which extend through the thickness of the seed disk. As the individual seeds are carried by the seed cells in the seed disk, they eventually reach a point where they must be released from the seed cells for discharge from the seed meter. This is accomplished by isolating the effects 20 of the vacuum from the seed cells in such a region.
In vacuum seed meters of the type described in the co-pending application of Lundie et al, it is necessary that the vacuum chamber within the seed meter housing be sealed so that the vacuum can be confined to the apertures within the seed disk which communicate with the seed cells. This requires sealing of the region between the outer periphery of the seed disk and the interior wall of the seed meter housing defining the vacuum chamber. Complicating this requirement is the fact that the seed meter rotates at a speed which can become quite substantial. An even further requirement is imposed by the necessity for cutting off the vacuum from that portion of the seed meter which is within the seed discharge area. These various requirements suggest the use of a seal between the inner wall of the seed meter housing and the seed disk in the region of the vacuum chamber so as to confine the vacuum to the apertures within the seed disk. At the same time, such seal must be capable of accommodating rotation of the seed disk, and must furthermore be capable of isolating a portion of the seed disk from the vacuum source.
It is known to provide flexible seals for use between a stationary member and a rotatable or otherwise movable member. Such seals are typically annular or circular in configuration and employ one or more relatively thin, flexible portions of a resilient sealing member or arrangement for bearing against the rotating or otherwise movable part. Examples of this type of seal are provided by U.S. Pat. Nos. 4,260,165 of Hartelius, 3,664,675 of Malmstrom, 3,713,659 of Derman, 3,703,296 of Malmstrom, 3,980,309 of Dechavaune, 3,504,917 of Malmstrom, 4,311,315 of Kronenberg add a product brochure on "V-RING" seals by Forsheda of Basle, Switzerland. Examples of other seals used in different sealing arrangements are provided by U.S. Pat. Nos. 4,375,292 of Ericson and 4,204,948 of Wechsler et al. While the various sealing arrangements noted in the patents and the article confront the problem of providing a seal between a moving part and a stationary part, and some address the situation in which a pressure differential is present or utilized in a sealing environment, none contemplate the particular problems discussed above in connection with a vacuum seed meter of the type shown in the previously referred to co-pending application of Lundie et al or suggest a solution thereto.
Accordingly, it would be desirable to provide an improved flexible seal for use between a stationary member and a rotatable or otherwise movable member. In particular, it would be advantageous to provide an improved seal for use with a vacuum seed meter in which a sealing relationship is maintained between the housing and a rotating seed disk and in which a portion of the seed disk is isolated from the vacuum source.